Published in the journal Nature - Scientific Reports:
Edith Cowan University research shows that seagrass covering 48,000 square metres (sqm) has been scoured from the sands of Rottnest Island by almost 900 mooring chains from recreational boats.
Australia has abundant seagrass meadows covering around 90,000 square kilometres of seabed off Australia's coast - roughly the size of Tasmania.
These meadows provide an important habitat for many species of fish as well as a food source for dugong and turtles.
Importantly, they also absorb carbon dioxide at a rate more than 40 times faster than tropical rainforests.
Consequently, when the seagrass meadows are wiped out, the carbon absorbed over hundreds of years is released as carbon dioxide into the atmosphere.
Concerns have been raised that seagrass meadows are dying off due to climate change, but other effects of human development are also posing a threat to these important ecosystems.
As the ECU study demonstrates, this includes the mooring chains of recreational boats, as their movement scrapes seagrass off the seafloor.
The research compared scarred areas with areas where seagrass meadows still exist. This revealed that in scarred areas on average more than 75% of carbon absorbed in seagrass meadows was lost.
Efforts to preserve seagrass meadows by using seagrass friendly mooring lines is resulting in the recovery of seagrass in some areas of the Island.
However, overall seagrass cover is decreasing as the size of mooring scars in Stark Bay on the Island's north coast has increased about 500% from 2,000 sqm in 1980 to 9,000 sqm today.
This is due to erosion of the already scarred areas by wave action.
According to Dr Oscar Serrano, once mooring chains start the process of scouring waves continue to spread those scoured areas. As a result, the researchers found in Stark Bay that the scarred areas join up to become large areas devoid of any seagrass, which has important implications for Perth's marine environment.